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CVE-2026-53920— odhcpd DHCPv6 Short IA_NA/IA_PD Body Stack Disclosure

Quick assessment

Affected
openwrt odhcpd
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

odhcpd 是 OpenWrt 所使用的 DHCPv6、DHCPv4 及路由器公告（Router Advertisement）服务器。在版本 17.01.0 至 25.12.3 之前的版本中，odhcpd 的 DHCPv6 IA（地址授权）解析器会接受一个 IA_NA 或 IA_PD 选项，其主体长度小于 结构体；随后，它将该选项头强制转换为该完整结构体，并在未先验证 IA 主体是否包含 IAID 字段的情况下，直接读取 。若未经身份验证的邻近网络客户端在 odhcpd 8192 字节的接收栈缓冲区末尾放置一个零

CVSS 8.7 · High

Affected Version Matrix 1

VendorProduct Version RangeStatus
openwrt odhcpd >= 17.01.0, < 25.12.3 affected
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I. Basic Information for CVE-2026-53920

Vulnerability Information
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Vulnerability Title
odhcpd DHCPv6 Short IA_NA/IA_PD Body Stack Disclosure
Source: CVE Program / CVE List V5
Vulnerability Description
odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. From version 17.01.0 to before version 25.12.3, odhcpd's DHCPv6 IA parser accepts an IA_NA or IA_PD option whose body is shorter than struct dhcpv6_ia_hdr, casts the option header to that full structure, and reads ia->iaid before proving that the IA body contains the IAID field. If an unauthenticated network-adjacent client places a zero-length or otherwise short IA option at the end of odhcpd's 8192-byte receive stack buffer, the IAID read crosses from data_buf into adjacent stack memory. The disclosed bytes are then reflected in the DHCPv6 reply IAID; prior ARM validation showed data_buf[8192:8196] disclosing the saved stack canary, and wider stack scans can leak ASLR-useful stack/process contents. This issue has been patched in version 25.12.3.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
openwrt odhcpd >= 17.01.0, < 25.12.3 -

II. Public POCs for CVE-2026-53920

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III. Intelligence Information for CVE-2026-53920

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Patches & Fixes for CVE-2026-53920 (2)

Vendor Advisories for CVE-2026-53920 (1)

Same Patch Batch · openwrt · 2026-10-23 · 4 CVEs total

CVE-2026-53921 9.8 CRITICAL odhcpd: Stack buffer overflow in DHCPv6 IA reply serialization (2 independent sites)
CVE-2026-53918 8.8 HIGH odhcpd DHCPv6 IA dangling first pointer use-after-free
CVE-2026-55606 6.5 MEDIUM odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()

IV. Related Vulnerabilities

Same product: odhcpd
Same vendor: openwrt
Same weakness: CWE-125

V. Comments for CVE-2026-53920

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